Cordell Bank National Marine Sanctuary

Cordell Bank was originally created 93 million years ago, as a member of the Sierra Nevada. The grinding of the plates at the San Andreas Fault, with the Pacific Plate moving north and the North American Plate moving south, parts of the Sierra Mountains were sheared off and carried northwards, including Cordell Bank. Eventually this grinding carried Cordell Bank to its present location opposite Reyes Point. Cordell Bank is still moving, by an average of per year. Between 20,000 and 15,000 years ago the sea level in the area was below the current level, leaving most of Cordell Bank exposed and making it a true island. Today the bank rises out of soft sediment, deposited on the bank more recently by coastal erosion. Within just of Cordell Bank, the continental shelf drops to over deep. The seamount is largely composed of granite. ==History==

Coastal California has a rich history of marine utilization by Native Americans and early settlers. Cordell Bank was a mystery prior to the 19th century because neither the Miwok natives nor the settlers had any incentive to venture far out from shore, when food resources were available close to shore. Many European mariners sailed right over Cordell Bank without even knowing it was there. In the later half of the 1800s there was a strong incentive to survey the coast of California so as to promote maritime safety. Cordell Bank was discovered in 1853 by George Davidson of the United States Coast Survey during a mapping expedition on California's north coast. In 1869 Edward Cordell (the reserve's namesake) was sent to collect additional information on a "shoal west of Point Reyes". He found the area by following the numerous birds and marine mammals. To measure the depth, Cordell lowered a lead weight into the water until it hit the bottom and then measured the length of the line on its return to the surface. In 2012, the National Oceanic and Atmospheric Administration proposed an expansion of the borders of the sanctuary, along with expansion of the Gulf of the Farallones National Marine Sanctuary, to include an additional 2,700 square miles, reaching to Point Arena. Expansion was passed March 2015. ==Biology==

in the sanctuary during a field trip for the Every Kid in a Park program in 2016. flips out of the water in the sanctuary. swims in the sanctuary. ) and strawberry anemones (Corynactis californica'') at a depth of in the sanctuary. swims past a colony of strawberry anemones (Corynactis californica) and orange hydroids (Garveia annulata ) in the sanctuary. Twenty-six species of marine mammals, including whales, dolphins, seals, and sea lions, are known to frequent the waters of the sanctuary. In addition, Cordell Bank is one of the most important feeding grounds in the world for the endangered blue and humpback whales; these species travel all the way from their breeding grounds in coastal Mexico and Central America to feed on the krill that aggregate near the bank. Another unique species is the Pacific white-sided dolphin (Sagmatias obliquidens), which can be seen in large numbers. Other visitors include California sea lions (Zalophus californianus), northern elephant seals (Mirounga angustirostris), northern fur seals (Callorhinus ursinus), and Steller sea lions (Eumetopias jubatus), all of which are attracted to the abundance in krill, squid, and juvenile fish. Leatherback sea turtles also inhabit sanctuary waters. Cordell Bank is also a major foraging ground for passing seabirds. Known as the "Albatross capital of the world," five of the 14 major species of albatross have been documented there. The two most common are the black-footed albatross (Phoebastria nigripes) and sooty shearwater (Puffinus griseus). It is also one of the few places to see a short-tailed albatross (Phoebastria albatrus), which is extremely rare; the species was thought to have gone extinct after World War II. Currently the world population hovers at around 1000 individuals. During the late summer and fall seasons, the coastal winds that stirred up the deeper waters die down, and the northward-flowing Davidson Current prevails, bringing warm but nutrient-poor water from the south. During the winter storm months, the sea is dominated by rough weather, which mixes the deeper water with that above. The temperature on top of the continental shelf mixes, and the temperature, salinity, and the concentration of nutrients in them are assimilated. ==See also==